Starscream was a Cybertronian and second-in-command of the Decepticons.
Millions of years prior to the 23rd century, Cybertron fell into civil war, Starscream joining the Decepticons, becoming the faction's second-in-command despite his traitorous ambitions and deep hatred for Megatron. Four million years ago, the forces unleashed by the war had ripped Cybertron from its orbit and it drifted into the path of the Sol asteroid belt, the rocks threatening to destroy it. Autobot High Command boarded a starship to clear a path through the field with Megatron's flagship attacking the Autobots once the hole had been created, Starscream among the boarding party. Passing too close to the nearby Earth however, the Autobot ship spun out of control and crashed into a volcano on the prehistoric planet, all aboard falling into stasis lock. In the 1980s, the volcano erupted, reactivating everyone and starting a secret war for Earth's supply of energon, Starscream and his armada reformatting themselves into contemporary F-15 fighter jets. In the year 2026, Earth fell to World War III. With Optimus Prime leading his forces off-world in search of more energon, the Decepticons followed in Trypticon. After trailing the Autobots for decades, the Decepticons attacked over Cygnus Seven, with history repeating itself as the Decepticon boarding caused the Autobot ship to fly out of control and crash land, knocking everyone into stasis. On stardate 5892.7, a dilithium survey team was exploring the caverns and unknowingly triggered Fortress Maximus' autonomic protocols. By random chance, Megatron was the first to be reactivated, healing his troops and leading an attack on the surface. (TAS - Star Trek vs. Transformers comic: "Issue 2")
Carrying his master in his cockpit, Starscream led his Seekers in a devastating attack on the colony before Optimus Prime arrived only to be wounded into stasis by Kirk's phaser. When the human captain demanded that the invaders identify themselves, Megatron simply ordered Soundwave to execute the organics. Soundwave's audio disruptor waves managed to pierce the static surrounding Cygnus Seven allowing Kirk to call the USS Enterprise for a photon torpedo strike. The Decepticons fell back to a nearby moon where they found Trypticon being investigated by Kuri's Klingons, the aliens disgusting Starscream. (TAS - Star Trek vs. Transformers comic: "Prime's Directive, Part One")
His pessimism soon spread to his comrades, the Decepticons only being won over when the Klingons revealed the existence of their cloaking device. As Trypticon scanned the downed D7, Starscream manipulated Kuri into granting him a personal cloaking device, appealing to the Klingon's sense of honor and victory. After Tryption had crippled the Enterprise, Starscream led the Decepticon ground forces back to Cygnus Seven. (TAS - Star Trek vs. Transformers comics: "Issue 2", "Issue 4")
Upon pinning Optimus Prime's group, Starscream demanded the Prime's surrender only for Spock to come forth before Optimus. Scoffing at the idea of sparing organics, Starscream prepared to execute Optimus before Fortress Maximus burst out of the moon's crust, forcing Trypticon back to robot mode for a duel. (TAS - Star Trek vs. Transformers comic: "Issue 3") Deciding to cut his losses, Starscream cloaked himself and stole a cache of dilithium as a substitute for energon only to be sighted by a furious Megatron as he left the planet. Jumping to warp, Starscream landed beyond the First City of Qo'noS, ready to conquer the planet. (TAS - Star Trek vs. Transformers comic: "Issue 4")
Taking a moment to download Klingonese, Starscream broke into the halls of the Klingon High Council, using his null-rays to stake his claim on the Klingon Empire before the city was subject to an orbital bombardment. Though initially suspecting the Autobots, the Decepticons descended on Starscream, Megatron knocking him down and executing him. (TAS - Star Trek vs. Transformers comic: "Issue 5")